/Engine/Source/Runtime/NavigationSystem/Public/NavigationData.h
Configures this NavData instance's navigation generation to be suspended or active. It's active by default. If Suspended then all calls to RebuildDirtyAreas will result in caching the request in SuspendedDirtyAreas until SetRebuildingSuspended(false) gets call at which time all the contents of SuspendedDirtyAreas will get pushed to the nav generator and SuspendedDirtyAreas will be cleaned out. Note that calling SetRebuildingSuspended(true) won't suspend the nav generation already in progress. Note2: due to all areas dirtied during generation suspension ending up in SuspendedDirtyAreas care needs to be taken to not use this feature for extended periods of time - otherwise SuspendedDirtyAreas can get very large.
virtual void SetRebuildingSuspended ( const bool bNewSuspend )